1. Field of the Invention
This invention relates to filters for cigarettes. In one aspect it relates to a filter with novel ventilating means therein. In another respect the invention relates to a filter cigarette having flow directing ducts therein for directing ventilating air toward the mouth end of the filter to be mixed at the outlet surface thereof. In even another respect the invention relates to a high ventilation cigarette wherein the smoke leaving the filter is instantaneously dispersed.
2. Description of the Prior Art
It is well known in the art to add filters or tobacco wrappers to cigarettes which provide ventilating air means to bring in ambient air to dilute the smoke stream. The dilution of the smoke stream reduces the quantity of smoke particulates as well as gas phase components which are delivered to the mouth of the smoker. A number of means have been proposed and are utilized for introducing ventilating air into the cigarette. For example, the wrapper for the tobacco in a cigarette can be made from a porous material which allows for introduction of air along the entire length of the cigarette where it mixes with the smoke stream passing therethrough thereby diluting the smoke in the stream. Also, the cigarette wrapper may be perforated at selected locations along the length of the cigarette which provides ports for the cigarette through which ventilating air enters. Even further, it is known to perforate the wrapper of the filter on the filter end of the cigarette to allow for ventilating air to enter the filter for dilution of the smoke stream. There have also been a number of suggestions for incorporating grooves within the filter plug for the cigarette in order to facilitate the addition of ventilating air into the smoke stream.
For example, U.S. Pat. No. 3,596,663 relates to a tobacco smoke filter provided with a corrugated porous plug wrap surrounding a filter element which is circumscribed by a tipping paper having flow-through perforations therein whereby ventilating air enters directly into the filter element or progresses down the grooves to the smoker's mouth. U.S. Pat. No. 3,490,461 relates to a filter for a cigarette wherein a tubular body of extruded thermoplastic material having a plurality of longitudinally extending grooves in the outer surface is joined to a filter element which is disposed within the tube or is adjacent thereto wherein ventilating air travels down the grooves and smoke travels through the tube. Other patents which relate to cigarette filters having grooves circumscribing the filter element for the introduction of ventilating air into the filtering end of the filter cigarette include U.S. Pat. No. 3,577,995; U.S. Pat. No. 3,572,347; U.S. Pat. No. 1,718,122; U.S. Pat. No. 3,788,330; U.S. Pat. No. 3,773,053; U.S. Pat. No. 3,752,165; U.S. Pat. No. 3,638,661; U.S. Pat. No. 3,608,561; West German Pat. No. 2,302,677; British Pat. No. 1,414,745; British Pat. No. 1,360,612; British Pat. No. 1,360,611; and, U.S. Pat. No. 3,910,288, the aforementioned British patents being directed to non-wrapped acetate filters.
In the manufacture of most ultra-low tar cigarettes, those having less than 5 milligrams of tar per cigarette as determined by the method published by H. C. Pillsbury, et al for "Tar and Nicotine in Cigarette Smoke", J. Assoc. Offic. Anal. Chem. Vol. 52, pages 458-462, dated 1969, commonly referred to as the Federal Trade Commission's accepted test method for determining tar and nicotine deliveries of cigarettes, a large amount of ventilating air is used to dilute the smoke leaving the filter. In present filter cigarettes, this large ratio of ventilating air to smoke forms a sheath of air around the smoke so that very little taste is experienced by the smoker.